Determination of ethinyl estradiol in solid dosage forms by high-performance liquid chromatography

A rapid, reproducible high-performance liquid chromatographic system for the determination of ethinyl estradiol in solid dosage forms consisting of a reversed-phase column with a mobile phase of 0.05 M aqueous KH2PO4-methyl alcohol (2:3) and fluorescence detection has been developed. This stability-indicating method is applicable to tablets containing ethinyl estradiol alone or in combination with methyltestosterone and progesterones. The procedure has been used for the determination of ethinyl estradiol in single tablets, stability samples, and dissolution medium. Recovery of drug substance added to placebo was from 97.3 to 101.5% in stability and single-tablet assays, and 95.4 to 102.2% in dissolution assays. Reproducibility studies gave relative standard deviations of 0.4-2.2%.